The present invention relates to a device for fastening and releasing a door's chain lock, which is capable of being released by hand.
Conventional door locking chains simply serve to prevent the possible illegal intrusion of strangers such as, for example, an importunate peddler and so on, by limiting the door opening to a certain degree thereby only allowing the receiving of letters or of seeing the face of an unspecified person.
As described above, a conventional chain lock has the drawback that it allows the door to be opened from the outside to the degree corresponding to the length of the door's lock only by means of a chain which is not secured by a lock. Namely, in such a case there may be a lock of security against persons peeping or throwing dangerous substances into the inside of the door's opening. No protection is provided from intrusion into the interior by the cutting of the chain.